Inhibition of keratinocyte growth by different Nepalese zanthoxylum species

A total of 11 methanol extracts obtained from four different Nepalese Zanthoxylum species were screened for their antiproliferative activity against the growth of human keratinocytes (HaCaT cells). The extract obtained from Z. armatum barks was highly active with an IC50 value of 11 micrograms/mL. Also, the extracts obtained from Z. oxyphyllum barks and roots with IC50 values of 53 and 57 micrograms/mL, respectively, showed potent activity. Their antiproliferative activity was not due to cytotoxic effects on cell membranes, as documented by the activity of lactate dehydrogenase released from the cytoplasm of keratinocytes, which did not exceed that of the control value. Rather, they also protected against radical-induced damage to model membranes stimulated with 2,2'-azo-bis(2-amidinopropane) dihydrochloride.